Assignment of Portal Role Files

I'm not certain this is the proper forum in which to post this, so please forgive me if not.

We would like to assign different Portal Role files, granting increasing functionality to our three main groups of Portal users (one for ESS-only users, one for RSS-users, one for power-users).

Is it possible to re-assign the Portal role file using Resource Manager, without impacting anything else on the user's security profile?

Thank you.